See Osterley From A Different Angle
Sessions times are:
Every Sunday from April 1st – October 28th:
12 noon, 12:45pm, 1:30pm, 2:15pm and 3pm, sessions last 45 minutes, with a minimum of 30 minutes on the water. All sessions must be paid for at least 15 minutes in advance or they may be offered to other people (you can pay on line up till midnight the day before).
Every Saturday from May 5th – September 29th
12 noon, 12:45pm, 1:30pm, 2:15pm and 3pm, sessions last 45 minutes, with a minimum of 30 minutes on the water. All sessions must be paid for at least 15 minutes in advance or they may be offered to other people (you can pay on line up till midnight the day before).